JP2001223615A - Assignment of demodulation element to receiver capable of simultaneously demodulating spread spectrum signals - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method that operates a spread spectrum communication receiver and assigns a spread spectrum signal to a demodulation element of the communication receiver. SOLUTION: This method is a method, by which a demodulator demodulates a current path group, the current path group includes on current path or over and includes a demodulation step where one corresponding demodulation element or more demodulates the one current path or more. Furthermore, this method is a method by which the receiver discriminates one survey group or more, and each survey group includes a specific combination between one new path or over and a current path whose number is zero or more. Moreover, this method discriminates the quality standard of the current path groups and the quality standard of the one survey group or more. Furthermore, this method assigns a group selected from the survey groups to a corresponding element of the demodulator in place of the current path group, on the basis of the comparison between the quality standard of the group selected from the survey groups and the quality standard of the current path group.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention Embodiments of the present invention relate to spread spectrum communication systems, and more particularly, to the assignment of spread spectrum signals to demodulation elements in a communication receiver.

[0002]

BACKGROUND OF THE INVENTION Wireless communication has become widespread in business, personal, and other applications, and as a result, this communication technology has continued to evolve in its fields. One such evolution includes the use of spread spectrum communications, such as the use of code division multiple access (CDMA) cellular communications. In this communication, a user station (eg, a handheld mobile phone) communicates with a base station, which typically corresponds to a "cell", or sector of a cell, as used in the art. While the user station moves, the positions of other cells each having a base station are fixed, so that the user station can communicate with one or more base stations at a time in the same frequency band. This operation is usually called soft handoff. As a result, in a simple example, the dual communication between the base station and the user station is performed by two different “paths”, ie, forward / reverse communication. That is,
A first path from the user station to the first base station, a second path from the user station to the second base station, a first path from the first base station to the user station, and a second base It is a second path from the station to the user station.

[0003] In actual CDMA communication, a wireless medium is used, so that the same communication transmitted from a base station to a user station may arrive at the user station a plurality of times at different times. Here, each different signal arriving is transmitted over the channel and arrives as a different "path". This is because the transmitted signal from the base station is reflected by the ground, mountains, buildings, and other objects with which the signal contacts.
In the art, these multiple signals are referred to as multiple paths or multipaths. As described above, a plurality of multipaths eventually arrive at the user station, but the channels from which each signal is transmitted are different, so that the phase, amplitude, and S / N ratio (SNR) of each path are different. May be. Therefore, in the communication between a certain base station and a certain user station, each multipath is a copy of the same user information, and since the arrival times are different, each path has time diversity with respect to another multipath. This results in different (uncorrelated) fading / noise characteristics in each multipath. However, as will be described in more detail later, other types of signals containing the same information may arrive at the receiver at different times. In order to distinguish between these other types of signals and multipath signals, the time diversity appearing in different multipaths is referred to as multipath diversity in the remainder of this specification.

[0004] Multipaths transmit the same user information to the receiver, but these paths are separately recognized by the receiver based on the arrival timing of each multipath. Specifically, as is well known in the art, CDMA communications are modulated using a spreading code composed of a series of binary pulses. This code is transmitted faster than the symbol data rate and determines the actual transmission bandwidth. Currently, the industry calls each CDMA signal transmitted with this code a "chip". Each chip corresponds to a CDMA code element. Therefore, the rate of the CDMA code is defined by the chip frequency. CD by chip
Using the communication of MA signals, multipaths that are temporally separated by a plurality of these chips can be distinguished at the receiving end. This is because, as is known in the art, CDMA
This is because the autocorrelation of the code is low.

To further illustrate, other types of signal diversity are known in the art, one of which is referred to as base station diversity. Specifically, from the above description, a user station may receive the same user information from two different base stations at the same time. Therefore, information received from a certain base station is said to have base station diversity with respect to information received from another base station.
Again, as long as these base station diversity signals are temporally separated and use different codes, they can be distinguished from each other at the receiving end.

In the prior art, after the reception path is identified,
The receiving station has decided to demodulate any of the paths. Specifically, it is known in the art to incorporate a demodulation circuit into a CDMA receiver, which typically includes a plurality of demodulation elements. For example, this type of demodulation circuit includes a rake combination circuit. In this technique, the name is derived from the concept of a rake with a "finger", where each finger corresponds to a different demodulation element. In current systems, this demodulation circuit includes four or six different demodulation elements, each of which can demodulate the receive path assigned to that element in parallel. Therefore,
In the prior art receiving different multipath or base station diversity signals, the receiver selects which path is assigned to which available demodulation element. Therefore, in this technique, it is necessary to determine which path is to be assigned to a demodulation element that is not currently in use.
Also, for a busy demodulation element, it must be determined whether reassignment is necessary. For reassignment,
Because the newly received path has preemption rights, the new path will replace the path that is assigned to the demodulation element and is currently performing the demodulation operation by that element.

[0007] The purpose of the process of selecting and demodulating a particular path is usually to optimize performance parameters such as frame error rate (FER) or symbol error rate (SER) or to reduce the possibility of impairment. Lowering the reliability of the communication link. An example of this is "DEMODULA" issued on February 6, 1996.
TION ELEMENT ASSIGNMENT I
NA SYSTEMCAPABLE OF RECE
U.S. Pat. No. 5,490,165, entitled "IVING MULTIPLE SIGNALS" (the '165 patent), discloses a method for demodulation element assignment in a CDMA communication system. The '165 patent provides different demodulation assignment methods depending on whether the receiving side is a user station or a base station. Each is described separately below.

[0008] In the '165 patent, the demodulation element assignment method for a user station mainly describes base station diversity. Specifically, the method of the '165 patent requires that the user station always assign a modulation element to at least one path of a signal transmitted from each different base station. Thus, the user station has a path from the new base station (ie, not currently demodulated by that user station)
, The user station unconditionally assigns a demodulation element to the reception path. This assumes that the user station is communicating with multiple base stations at that particular time, that is, the user station is in soft handoff.
If the user station is not in soft handoff, or if the user station has assigned a demodulation element to each base station that is not performing soft handoff, the remaining unassigned demodulation elements will be SNR (or signal-to-interference ratio (SIR)) )
Are assigned to large paths. Also, if at least one demodulation element is assigned to all base stations communicating with the user station, all paths except the strongest path from each base station (that is, the maximum SNR or SIR) are released. , The modulation element can be reassigned to the path with the higher SNR.

[0009] Having introduced soft handoff above, some other things known in the prior art relating to soft handoff are described below. When the first path from the new base station is assigned to the user station demodulation element,
The soft handoff process starts. This is usually determined by the system controller. The user station receives a notification from the base station currently supporting communication that the new base station has started transmitting to the user station. This allows the user station to assign one or more paths from the new base station to the demodulation elements.

[0010] Returning to the '165 patent, the demodulation element assignment method for the base station assumes that the input path diversity is only multipath diversity. Under this assumption, for each signal that the base station receives from the user station, the demodulation element assignment is based on the received path SN
It all depends on R. Therefore, a path having a large SNR is assigned to the demodulation element. Also, both the user station and the base station assumed a typical hysteresis method commonly known in the literature.

Although the '165 patent provides a method for base station or user station demodulation element assignment, the inventor of the present invention has recognized that the method has several disadvantages. One of the drawbacks is that for user stations, performing the '165 unconditional assignment (ie, allocating to arriving signals from new base stations) based on base station diversity, may require demodulators It will not be used optimally. For example, if the SNR of the path from the first base station is very large or for other reasons, the path from the first base station will benefit the receiver over the path from the second base station. Even so, the demodulation element assigned to the second base station path is occupied and cannot be used to demodulate the path from the first base station.

As another disadvantage, the assignment method of the '165 patent provides only one type of diversity for user stations (ie, base station diversity).
No consideration is given to the diversity of the signals received by the base station (that is, only the SNR is evaluated). However, there are some other types of diversity in CDMA signals, as recognized in the art beyond demodulation. Thus, due to these other diversity types, the same station may receive different paths in the same time. In this case, the signal may contain the same user information, but some characteristics of the path carrying the information may differ in some respects from other paths received in the same time. For example, if the base station uses multiple antennas and sends the same signal from each antenna to the user station, multiple paths will arrive at the user station. In addition, when the user station uses a plurality of antennas to distinguish arriving signal paths (that is, at least one path for each receiving antenna), a plurality of signals may be generated. In addition, several other diversity types are known in the art. For example, angle diversity (e.g., paths arriving on different electromagnetic surfaces) and code diversity (signals transmitted with different spreading codes), and some more diversity types can be ascertained by those skilled in the art. Last but not least
It should also be noted that some or all of the causes of multiple paths described above may also occur in the reverse direction, i.e., in the communication link of signals transmitted by the user station and received by the base station. These other types of diversity are '1
It is not explicitly considered in the method of the '65 patent. Furthermore, these various diversity cannot be determined to affect SNR and are not necessarily implicitly considered in the method of the '165 patent. However, in the embodiments of the present invention, as described in detail below, the inventor of the present invention has realized that some or all of these diversity types are implemented in the preferred embodiments described below. We realized that the process of selecting a path for demodulation was valuable.

[0013]

The preferred embodiment provides a method of operating a spread spectrum communication receiver.
The method demodulates a current path group with a demodulator, wherein the current path group includes one or more current paths, and the demodulating step demodulates one or more current paths with one or more demodulation elements. Including the step of: The method also comprises determining one or more new path groups (survey groups) on the receiving side, where each survey group has a different combination of one or more new paths and zero or more current paths. including. Further, the method determines quality criteria for the current path group and the plurality of survey groups. Each survey group includes one or more new paths and zero or more current paths. Further, the method selectively assigns the selected survey group to a corresponding element of the demodulator instead of the current path group. This assignment is based on comparing the quality criteria of the selected survey group with the quality criteria of the current path group,
Conducted when the quality standard of the survey group is higher than the quality standard of the current group. The selected survey group is
It has the highest quality standards in all survey groups. The quality criterion is also determined by the power or signal-to-noise ratio of each path in the group and a plurality of diversity types in the group. Other circuits, systems, and methods are also disclosed and claimed.

[0014]

FIG. 1 shows a diagram of a cellular communication system 10 as a current example in which the preferred embodiment operates. The system 10 has two base stations BST1 and BST
2, each operating according to methods commonly known in CDMA technology. Further, each of the base stations BST1 and BST2 has two antennas so that CDMA signals can be transmitted and received from each antenna. By convention, each antenna will be followed by the abbreviation AT followed by a number to indicate its own base station distinction, followed by the base station identifier. For example, the base station BST1 includes a first antenna AT1B1 and a second antenna AT2B1. Similarly, base station BST2 has first antenna AT
1B2 and a second antenna AT2B2.
The general area covered by each base station defines the corresponding cell. Accordingly, base station BST1 is generally adapted to communicate with other cellular devices in cell 1 and base station BST2 is generally adapted to communicate with other cellular devices in cell 2. Of course, considering that the communication station moves from one cell to another cell, cell 1
There is some overlap between the communication range of cell and cell 2 by design to support continuous communication. In fact, to further illustrate this point, system 10 includes user station U
ST is also included. This user station is shown with the vehicle V, indicating that the user station UST is mobile. Further, as an example, the user station UST includes one antenna ATU so that both transmission and reception of cellular communication can be performed.

In many respects, system 10 can operate in accordance with various well-known techniques of cellular or other spread spectrum communications, including CDMA communications. Such general techniques are well known in the art, and when a call is initiated from a user station UST, the base station BST1
And / or BST2 handle the call. In addition, the prior art includes a technique called soft handoff. This is further enhanced by the preferred embodiment described below. Here, it is simply mentioned that the soft handoff is a process executed when the user station UST exists in an area near a common boundary between the cell 1 and the cell 2. For example, assume that the user station UST is in progress from a position near the base station BST1 to a point near the base station BST2. The base stations BST1 and BST2 detect this change in the relative physical position by processing the signal communication from the user station UST. Also, the user station UST has a new base station BS.
The base station BST which recognizes a sufficiently strong signal from T2 and currently supports communication with the user station UST
Notify 1 to that effect. The base station BST2 is now a candidate for soft handoff. The system controller can determine the start of the soft handoff process based on the resources available at the base station BST2 and other system conditions. Initially, at this point, the base stations BST1 and BST
2 transmits a signal containing the same information to the user station UST
And the user station UST correctly identifies and demodulates these signals so that the user of the user station UST can sense the reception of only one information data stream. But,
As the user station continues this path, the controller can take appropriate control actions. This control means that one of the base stations (for example, BST1) is connected to the user station UST.
This is a control in which communication with the user station UST is finally stopped (interrupted), and the other base station (for example, BST2) continues communication with the user station UST. This process is preferably performed such that the user station UST is not known. Thus, in this method, one base station "hands off" communication with another base station.

FIG. 2 shows a receiver 20 according to the preferred embodiment.
It is a block diagram of. Here, an outline of the structure and operation is introduced. Before proceeding, it should be noted that the steps included in the blocks of FIG. 2 and subsequent operational diagrams are for purposes of illustrating and describing particular functions. The actual circuits, software,
Or the firmware (or a combination thereof) can be implemented using a digital signal processor or other methods, as will be appreciated by those skilled in the art. Further, the receiver 20 can be used at one or both of the user station and the base station, and thus can be used at all of the BST1, BST2, and UST stations of FIG. Finally, it should be noted that the block diagram of FIG. 2 is only an example of a setup for functionally performing the method of the present invention described below, so that these blocks will be That is, it can be rearranged in another way or changed by those skilled in the art. Indeed, while the following description is functionally accurate in that it can be subdivided, the overall functionality may use different block formats or separate the functionality described below into components of the receiver 20. This can be achieved by:

The receiver 20 receives a CDMA signal at an input 22.
, Whose input is connected to a despreading block 24. The despreading block 24 operates according to well-known principles (eg, multiplies a CDMA signal by the CDMA code of the receiver 20) and outputs at its output a despread symbol stream at the symbol rate. Specifically,
In a preferred embodiment, despreading block 24 (or other blocks if desired) includes an element referred to in the art as a searcher (not separately shown). The searcher first determines the number of identifiable passes. These paths typically contain CDMA codes that are separated or different in time than one chip interval and are received to perform a particular communication. Upon receiving the paths, the despreading block 24 sets up buffers for each of these paths after despreading. The output of the despreading block 24 is connected to an SNR measurement block 26, a demodulation element allocation block 27, and a demodulator 28.

The SNR measurement block 26, as the name implies, measures the SNR (or signal-to-interference ratio (SIR)) at the output of the despreading block 24 and supplies this measurement to a demodulation element allocation block 27. The reason will be described later in detail. Further, the SNR measurement block 26
Also receives input from input 22. Upon receiving two inputs, block 26 determines the noise power N from the signal before being despread by despreading block 24,
6 is the signal power P after despreading by block 24
Is determined. From these two measurements, the SNR is P / N
Is determined. But in any case, S
Since NR measurements are common in wireless receivers for several reasons, it is assumed that receiver 20 already has this feature, and that the output of despread block 24 (and elsewhere) is Can be used for measurement.

A demodulation element assignment block 27 receives all despread signals and determines which of these signals to assign to demodulator 28. That is, one of the despreading elements of the demodulator 28 is “assigned”. More specifically, the output of block 27 informs despreading block 24 of this decision so that the despreading block can only connect the selected signal to demodulator 28. Thus, although the output of block 24 is shown as connected to the input of demodulator 28, the selected signal is coupled from block 24 to demodulator 28, but not selected. The resulting signal is not passed to the demodulator 28. Further, upon receiving the selected signals, demodulator 28 demodulates only those selected signals using the corresponding demodulation elements. A preferred embodiment in which the demodulation element assignment block 27 selects a signal will be described later with reference to FIG. Inputs from the SNR measurement block 26, the demodulator 28, and the path diversity determination block 29 to the block 27 will also be described later. Note that the demodulator 28 of the preferred embodiment includes an integer M demodulation elements, each of which operates to demodulate that path once that element is assigned a path. deep. For example, the demodulator may be constructed using a rake combination circuit (as described in the Background section of this specification), which includes demodulation elements known in the art as fingers. ing. In any event, demodulator 28 combines the results of each demodulation element, thereby outputting a single symbol stream (not a "pass"). This single stream is the result of the operation of demodulator 28. Here, the demodulator combines the respective component signals by various techniques called maximum ratio combination in this technique. 1
In a method, these operations are described in US Patent No. 09 / 452,066, filed November 30, 1999, "Channel.
Estimation For Communicat
ion SystemUsing Weighted
Estimates Based On Pilot
Data and Information Dat
a ". In any case, the single symbol stream output by demodulator 28 is an estimate of the transmitted information data (also called" soft data "). The single symbol stream output of demodulator 28 is connected to decoder 30.

The decoder circuit 30 includes a deinterleave
, Viterbi decoder, or turbo decoder,
Or include any other suitable decoding method known in the art.
Can be. The decoder 30 also typically provides a specific error.
-Decoding the correction code and the soft data symbols used
And output the resulting decoded symbol stream.
Power. Actually, data input to the decoder 30 has an error.
The probability that an error occurs is processed by the decoder 30 and output.
It is much larger than the probability after being forced. For example,
According to current standards, the error rate at the output of the decoder 30
Is 10^-3From 10 ^-6Between. Finally, the decoder 30
Output from the receiver 20
And received and processed by other circuitry within. However, the book
For simplicity, the circuit is shown in FIG.
I haven't.

FIGS. 3a and 3b illustrate a method 32 of operation of the demodulation element assignment block 27, which relates to receiving a path and assigning these selected paths to demodulation elements. Before explaining this, method 32
Can be implemented using additional circuitry for the control and / or state machine included in the receiver 20. These are, for example, the demodulation element allocation block 2
7, and those skilled in the art will readily understand several methods for implementing the steps described below. In method 32, typically for some signals received by receiver 20, these one or more signals are demodulated by demodulator 28.
Are assigned to the M demodulation elements included in. To further illustrate this operation in conjunction with the following detailed description, FIG.
Use the example using the context of In this example,
Assume the following: First, the receiver 20 is an element of the user station UST, and its demodulator 28 includes two demodulation elements (ie, the integer M is 2). Second
At a particular point in time, it is assumed that each base station BST1 and BST2 transmits a signal to the user station UST using each antenna. Therefore, in the base station BST1,
Antenna AT1B1 sends a signal to user station UST, and antenna AT2B1 also sends a signal to user station UST.
The same applies to the two antennas of the base station BST2. Therefore, under these assumptions, a total of four signals are sent to the user station UST. But ultimately,
It is assumed that each signal to be transmitted creates two multipaths, which, when they arrive at the user station UST, will be offset in time from each other. Thus, from all these assumptions, a total of eight paths are received by the user station UST, and these different paths are abbreviated as shown in Table 1 below. Here, in the notation (x, y, z), x is a transmitting base station, y is a base station antenna, and z is a number that distinguishes each of two multipaths transmitted from a specific antenna.

Examining the specific steps of method 32, method 32 begins at step 34, where one or more signals (or "paths") are received at input 22 and sent to despreading block 24. hand over. In this example, it is assumed that each of the eight paths shown in Table 1 is received by this method. In step 34, despreading block 24 despreads the input path in a manner well known in the art. For example, the despreading block 24 uses a locally generated duplicated CDMA code (synchronized with the arrival time of the receiving path) and a correlator to separate the desired path from all other signals and paths. . A CDMA correlator can be considered a matched filter. That is, a CDMA that matches its own code
Responds only to code-encoded signals. Thus, a CDMA correlator can be "tuned" to different signals simply by changing its local code. The correlator does not respond to intentionally created, naturally occurring, or artificially generated noise or interference. Only responds to spread spectrum signals that have identical signal characteristics and are encoded with the same CDMA code. If the timing is correct and the settings of the other receivers are correct, the correlation result produces the original transmitted signal (affected by channel and interference / noise) and the remaining interfering signals are considered noise . This is a direct result of the pseudo-noise characteristics of the CDMA code. Next, method 32 includes step 36
Proceed to.

In step 36, the despreading block 24
Identify paths that can be identified. Specifically, as previously mentioned, the despreading block 24 (or other blocks, if desired) includes a searcher. The searcher first determines the number of identifiable paths received for a particular communication. An identifiable path is typically a path that is temporally separated by more than one chip interval or that is assigned a different CDMA code. In response to this result, the despreading block 24 sets a buffer for each of these despread paths. Therefore, in this example, it is assumed that the searcher has correctly identified each of the eight paths in Table 1 and that each path is stored in a corresponding buffer. Next, the method 32 proceeds to step 38.

In step 38, the SNR measurement block is:
The SNR (or SIR) of each path output from the despreading block 24 is measured. These SNR values are used in demodulation element assignment block 27, as described in more detail below. Thus, in a preferred embodiment, each measured value is stored and made available for subsequent analysis. The meaning will be described later in detail. Next, method 3
2 proceeds to step 40.

At step 40, the demodulation element allocation block 27 determines the identification parameters for each path, ie, the parameters related to the diversity type of that path. These identification parameters identify the base station of each signal (thus detecting base station diversity) and multipath (thus detecting multipath diversity), as in the prior art. For example, to explain this point, in step 40, in the case of the path 1 in Table 1, these two identification parameters determine that the path is from the base station BST1 and is the first multipath. Also, in the case of path 2 in Table 1, step 40 determines that these two identification parameters indicate that the path is from base station BST1,
It is determined that it is the second multipath. However, step 40 determines other identification parameters related to the diversity type in addition to these determination items. That is, the determination of the diversity is not limited to the base station diversity and the multipath diversity. For example, such other identification parameters for diversity include, but are not limited to, the examples of diversity described in the Background section of this specification. Therefore, these examples include identification of a particular transmitter antenna (ie, transmitter antenna diversity when the transmitter has multiple antennas),
Antenna for a particular receiver Identification of the receiver (ie, receiver antenna diversity when the receiver has multiple antennas), Identification of the angle of signal reception (ie, the angle at which the signal arrives at various electromagnetic surfaces) Diversity) and identification of extension codes (ie, code diversity when signals are transmitted with various extension codes). In addition, there are also identification parameters that may be different for some or all transmitted signals, such as various frequencies (ie, frequency diversity) and coding and interleaving efficiency. Finally, step 4
0 indicates that any input and function described for block 27 in this specification can be performed. For example, as previously mentioned, the searcher can distinguish between multipath and base station diversity and block 27
Can use this information. As another example, a path diversity determination block 29 is also shown. This is to generally represent other diversity types (eg, receiver antenna diversity, transmitter antenna diversity, angle diversity, etc.) that can be determined by other circuits and / or software.

To describe the operation of step 40 in more detail, the path of Table 1 will be described.
X (ie, base station diversity) of those paths, y
(Ie, base station antenna diversity) and z (multipath diversity) are determined. However, if there are one or more additional diversity parameters in the path of Table 1, step 40 may include not only the above parameters but also
Also identify those additional parameters. Also in this regard, the detection of the identification parameter depends on the diversity type, and if this step is selected to incorporate a certain diversity type, those skilled in the art can easily understand how to identify the diversity type. Please note. To give an example of identification parameter detection, multipath diversity is detected by a searcher. In this case, the searcher identifies these paths by scanning a window of time offset at the nominal time. Specifically, it is well known that the difference between the arrival times of multipaths transmitted from the same transmitter falls within a known range depending on the communication environment (indoor, outdoor, etc.). Thus, the searcher element can identify multipath by looking up the nominal arrival time or indirectly referring to the arrival time. To do so, it correlates the expected replica of the received signal at each possible time offset and uses the result to determine whether a path exists at that particular offset. In this way, various transmitters (for example,
Multipaths can be identified as in the case of paths from various base stations. As another example of identification parameter detection, for paths receiving at different frequencies (frequency diversity) or at different angles (space diversity), multiple antennas can be used at the receiver side to identify and separate them. As yet another example of identification parameter detection, receiving a signal corresponding to a signal transmitted using a different spectrum extension code (code diversity), which does not mean that the same code has a different offset. A different spectrum extension code can be used for demodulation on the side. In any event, once the identification parameters have been identified, method 32 proceeds to step 42.

In step 42, based on the paths identified in step 36, demodulation element assignment block 27 determines all possible "survey groups" for those paths.
Identify. These groups can be assigned to demodulation elements. To understand the meaning of this term, finally after step 42 and subsequent steps, the preferred embodiment assigns one or more paths identified in step 36 to corresponding one or more demodulation elements. Note that there is a possibility of demodulating the elements of Therefore, a survey group is a group of paths to be allocated, and is a group in which any of these groups can be allocated to a demodulation element at a specific time. Therefore, the term "survey" is used because, for each "group", we consider or "survey" whether each path in that group can be assigned to a demodulation element. . Further, each "group" is made up of a set having the paths identified in step 36, and for each group the number of paths is equal to the number M of demodulation elements.
The number of unallocated paths included in each survey group is equal to the number of demodulation elements to be reallocated, and the remaining paths included in each group are already allocated paths. The combination of paths in each group is different from other combinations of available paths (ie, other survey groups). Finally, as discussed below, the total number of groups depends each time on the maximum allowed number of demodulation element reassignments.

To further define step 42, the number of demodulation elements available for assignment is denoted as K. In addition, K must first be a known number to define a survey group. This is because, assuming that all available demodulation elements can be reassigned at one time, this number defines the maximum number of unassigned paths that can be incorporated into each survey group. . This number defines the total number of survey groups by specifying an unallocated path and an allowable combination of allocated paths. Note that the total number of paths included in each survey group is equal to the total number of demodulation elements M.
For example, if eight paths are identified in step 36 and only two demodulation elements are available for assignment of each path (i.e., K = 2), each survey group consists of at most two unassigned paths. This is because the number of paths that can be reallocated is that number. Thus, in this case, each survey group has no more than two unassigned paths, and in fact, some groups, as described below,
The number of unassigned paths must be less than K. Similarly, if three demodulation elements are available for assignment, each survey group will contain up to three unassigned paths. The same applies hereinafter. In general, if only K out of a total of M demodulation elements are available for reassignment at a time (K <= M), the survey group can include up to K paths different from the already assigned paths. , At least M-
It contains K assigned paths. Finally, in the example applied to FIG. 1, the receiver 20 includes a maximum of two demodulation elements (that is, M = 2). The remaining description of the current example assumes that both of these demodulation elements are available for assignment (ie, K = M = 2). However, in some cases, K is smaller than M, as described below. In this case, each survey group composed of a total of M paths can include K or less unallocated paths.

To illustrate the operation of step 42 and the concept of a survey group in more detail, the following description will take this group from the example of Table 1. Further, in this example, it is assumed that all the M demodulation elements can receive the demodulation target path when performing the identification analysis processing in step 42. Assuming these, M
Considering the example of FIG. 1 where is two demodulation elements, each survey group includes one or two different unassigned paths, each of which has one or two available demodulation paths. Assign to an element. Further, as already mentioned, in each survey group, the combination of paths is different from other combinations of available paths. Moreover,
As mentioned above, Table 1 includes eight different paths (ie, two different base station diversity types, two different base station antenna diversity types, and two different multipaths). Diversity). Thus, the total number C of the different combinations of these N (ie, N = 8) different paths is a survey consisting of only two paths, each corresponding to two available demodulation elements. The group can be represented by the following Equation 1.

Thus, from equation 1, it can be seen that in the example of FIG. 1, there are a total of 28 different survey groups identified in step 42. These 28 survey groups are numbered in Table 2 below and are indicated by the pass numbers in Table 1. Accordingly, Table 2 shows a combination of different paths included in different survey groups, and each group includes two paths to which available demodulation elements are allocated. For example, in survey group number 1, if one survey group includes paths 1 and 2, and this group number 1 is finally selected for assignment to two demodulation elements, path 1 and path 2 2 are demodulated by these elements. Further, the actual group to be used for reassignment among the total of 28 groups differs depending on various factors. For example, if a survey group contains only paths that have already been assigned, this group is not included in the reassignment process. In another example, some groups include one path that has already been assigned. If only one demodulation element reassignment is allowed at a time,
Only survey groups that contain only one unassigned path are considered. The remaining survey groups are not included.

Table 3 below shows the same survey group information as Table 2, but instead of using pass numbers,
Shows the actual path abbreviations taken from Table 1. Therefore, Table 3 also shows various combinations of paths included in various survey groups. Looking again at the survey group number 1 example, survey group number 1 includes (BST1, AT1B1, 1) and (BST1, AT1B1, 2) (that is, path 1 and path 2 in Table 1). ing. Thus, if survey group number 1 is ultimately selected for assignment to the two demodulation elements, one of these two demodulation elements will be the first multipath from the first antenna of base station BST1 (ie, (BST1 , AT1B1, 1)),
The other of the two demodulation elements is the second multipath from the first antenna of base station BST1 (ie, (BST1, AT
1B1, 2)) are demodulated.

In one embodiment, step 42 also performs a process of arranging some survey groups in a particular order for reasons that will become apparent later. More specifically, this processing is executed for a plurality of survey groups including paths that differ only in multipath diversity. That is, there is at least one path with the same identification parameter in each group and at least one path in another group. For example, in Table 3, survey groups 2 and 8 are examples of this special case. In particular,
The second paths of survey groups 2 and 8 are the same, but the first path is a multipath with the same diversity format (except for time diversity). In this specification,
Such a survey group is called a multi-path diversity only (MDO) survey group. In any case, for the MDO survey group, since the SNR of each path was measured in step 38, step 4
0 indicates a group belonging to the same MDO survey group as S
Arrange in descending order of NR. Referring again to the survey groups 2 and 8, assuming that the path (BST1, AT1B1, 1) has a higher SNR than the path (BST1, AT1B1, 2), the survey group 2 has a higher reassignment than the survey group 8. Is always preferred, so there is no need to look into survey group 8. In Table 3, examples of other MDO survey groups include survey groups 3 and 9, survey groups 4 and 10, and survey groups 5 and 11.

Having determined all possible survey groups and the identification parameters that will produce diversity in these groups, steps 48-58 determine whether it is advantageous to assign any of the survey groups to the demodulation elements. I do. At the beginning of the method, the advantage analysis considers whether making such an assignment would provide a significant improvement over the current state of the demodulation elements. For example, in a demodulator having M demodulation elements, if one or more of these elements are not assigned to any path at any time, demodulation is not performed and the unassigned demodulation elements are effectively used. Not necessarily. Thus, by definition for this case, allocating paths to unassigned demodulation elements ensures that the efficiency of use of the demodulator is improved. But,
In another example, all M demodulation elements may be assigned to each path and currently demodulating that path. Thus, in this case, the benefit analysis of the preferred embodiment performs what is effectively called a "what if" analysis. That is, in a preferred embodiment, a study group that includes one or more paths that are not currently assigned (hereinafter referred to as a “survey” group) is made up of one or more paths that are currently assigned to a demodulator. A determination is made as to whether there is a communication advantage when assigned to one or more demodulation elements instead of a group (hereinafter referred to as the "current" group). Therefore, in general, compared to the current group,
If demodulating the survey group significantly improves the frame error rate and / or other reliability of the decoding operation, remove or de-allocate the current group from the demodulation element and replace the current group with: Use survey groups instead, ie assign to demodulation elements. Further, some, if not all, of the M demodulation elements may already be assigned to each path. The preferred embodiment takes this possibility into account. The assignment process is the same for unassigned demodulation elements. In other words, there are M groups of paths and there are some paths other than the already allocated paths, and the group whose number is at least equal to the number of unallocated demodulation elements is to be investigated.

In the preferred embodiment, the benefit analysis described above is based on a comparison of various discriminant values. In this specification, each discrimination value is called a quality standard. A quality criterion is a measure of the value associated with a path group, and the groups for which the quality criterion has been determined can take different forms. In one example, the quality criterion is performed on a group consisting of the current path. In another example, the quality criteria is for a group that can replace the group of the current path. Such a replacement group may consist only of new paths or a combination of one or more new paths and zero or more current paths. Each quality criterion is based on the following two factors, as detailed below. (1) different diversity (if any) for all paths included in the currently targeted group and (2) SNR of the targeted group
(Or other power measurements). Each of these aspects can be understood in further detail by reading the description of steps 48 through 58 described below.

In step 48, demodulation element allocation block 27 determines, based on information from demodulator 28 or SNR measurement block 26, whether there is a reason to deallocate any of the currently allocated paths. This is why the output from demodulator 28 to block 27 is shown in FIG. For example, the demodulator 28 includes a time tracking device and the corresponding path no longer exists, or multiple paths are grouped together and multiple demodulation elements are assigned to the same path. , Etc. can be determined. In such a case, the receiver 20
Can de-assign one or more demodulation elements previously assigned to the paths and label them indicating that they can be used for new assignments. As another example, a similar indication may be obtained based on measurements from the SNR measurement block 26 for the assumed assigned path. Other reasons for deallocation can be understood by those skilled in the art. In any event, if the reason for the deallocation is detected, method 32 proceeds to step 50, where the path identified as being subject to deallocation is deallocated from the corresponding demodulation element. These elements are subsequently treated as empty or unused elements. The flow proceeds to step 51.

In step 51, the demodulation element block 27
Determines whether there is currently a survey group to be analyzed. If there is no such survey group, the method 32 proceeds to step 64 and completes the method as described below. Further, when the receiver 20 does not detect a new path, a situation may occur at step 51 where no survey group exists. Meanwhile, 1
If more than one survey group exists, use method 32
Goes to step 52.

At step 52, demodulation element allocation block 27 determines the quality criteria of the current group. Next, at step 53, block 27 determines the quality criteria of the survey group generated by replacing one or more paths of the current group with one or more paths. To illustrate these concepts, consider the following two examples.

As a first example of quality criterion discrimination in step 52, a demodulator having two elements is connected to a path A at an arbitrary time.
Assume that it is assigned to path B demodulation. Next, it is assumed that a new target path C has been added. In response, in step 52 the current group (ie,
A, B) quality standards are determined. Next, step 53
Determines the quality criterion of one of the two survey groups identified in step 52 under the conditions of the path assumed in this example. Thus, under this condition, the two groups are comprised of a first survey group consisting of (A, C) (ie, if new path C replaces current path B) and (B, C). And the second survey group (that is, when the new path C replaces the current path A). Therefore, in this example, it is assumed that the quality criterion of (A, C) is determined in step 53 first. As described below, method 32 includes a cycling operation to perform subsequent steps. In this circulation step, in one embodiment, step 4
Step 53 is repeated for each of the different survey groups identified in Step 2. Therefore, if step 53 is repeated twice in this example, step 53 determines the quality criterion of (B, C).

As a second example of the quality criterion discrimination in step 52, a demodulator having two elements is connected to a path D at an arbitrary time.
-Assume that it is assigned to demodulation of path E.
Next, assume that two new paths F and G are also to be assigned. In response, step 52 determines the quality criteria for the current group (ie, (D, E)).
Next, step 53 determines the quality criteria of the survey groups that have not been processed in step 53 among the survey groups identified in step 42. Thus, in this example, if two demodulation element reassignments are allowed, the survey groups identified in step 42 include (F, G), (F, D), (F, E), (G ,
D) and (G, E). If only one demodulation element reassignment is allowed, the survey group (F,
G) is not identified in step 42 (because two demodulation elements need to be assigned). Another option is that if any of the above is an MDO group, then only the group with the highest total path SNR is considered, which was previously described but will be described in more detail later. I do. In any case,
Step 53 finally determines the quality standard of each of these survey groups by executing the above-described circulation flow again. In addition, the measurement of these quality standards
A subsequent step of method 32 is performed to select any of the groups for demodulation, the criterion being that the quality criterion is at a maximum.

Having described the different groups that perform quality criteria, we now turn to each criterion. Specifically, as described above, the quality criterion of the group is different diversity (if any) within the group and S
This is performed based on NR. Second, note that in the preferred embodiment, for each path in the group, the quality criterion is the sum of the path's actual SNR and a value referred to herein as a "diversity value." Here, the diversity value is expressed in the same unit as the SNR (for example, dB), and the sum can be expressed in these units. The diversity values are based on the values recognized in one or more different identification parameters (ie, the parameters defining each diversity) for different paths in the group or those values were not specified, Evaluated for all paths in the group. This is described in more detail below using the first example shown above in the survey group example.

In the example of the first survey group described above, the current group (that is, (A,
B)) and then repeat step 53 to obtain two survey groups (ie,
(A, C) and (B, C)). In the following description, path A and path B are both shown in FIG.
It is assumed that the signal C is transmitted from the same antenna AT1B1 of the base station BST1 and the signal C is transmitted from the antenna AT1B2 of the base station BST2. Assuming the above, in the step 52 of determining the quality criterion of the current group, the actual SNR of the group is added to the diversity values of the diversity represented by A and B. However, since the signals are transmitted from the same base station with the same antenna, the diversity of A and B is only multipath diversity. In a preferred embodiment, the multipath diversity is preferably provided with a reference diversity value of 0 dB for reasons to be described later. Therefore, the quality criterion of the group (A, B) is only the SNR of the path A and the path B. As an example for later use, path A is 2 dB SNR and path B is 4 dB.
Let it be dBSNR. Therefore, the quality criterion of the current group consisting of path A and path B is 6 d
B (that is, 0 + 2 + 4 = 6 dB). Next, in step 53, the quality criterion of the first survey group composed of (A, C) is determined. Here, since path A is transmitted from base station BST1 and path C is transmitted from base station BST2, these two paths have base station diversity. Therefore, in step 53, the diversity value given to this type of base station diversity is added to the SNR of path A and path C, and the result is used as a quality criterion. For example, assume that the diversity value given to this base station diversity is equal to 4 dB. Also,
It is assumed that the SNR of the path C is 3 dB. Therefore,
The quality criterion for the (A, C) survey group is equal to 9 dB (ie, 4 + 2 + 3 = 9 dB). At the time of the second execution, in step 53, the quality criterion of the second survey group composed of (B, C) is determined. Again, path B is transmitted from base station BST1 and path C is transmitted from base station BST2, so there is base station diversity in the two paths. Therefore, in step 53,
The base station diversity value is added to the SNR of paths B and C, and the result becomes a quality criterion. Again, the diversity value given to this base station diversity is equal to 4 dB,
And under the above SNR assumption, the quality criterion of the survey group composed of (B, C) is equal to 11 dB (that is, 4 + 4 + 3 = 11 dB).

In step 54, it is determined whether the quality criterion of the survey group determined in the immediately preceding step 53 is higher than the quality criterion of the current group. Therefore,
In the first example above for a survey group of either (A, C) or (B, C), at the first execution of step 54, the quality criterion of (A, C) (ie, 9d
B) is compared with the quality criterion of the current group (ie, 6 dB), and (B,
Compare the quality criterion of C) (ie, 11 dB) with the quality criterion of the current group (ie, 6 dB). Thus, in this example, step 54 determines that the quality criteria of both survey groups are greater than the quality criteria of the current group. Therefore, every time these comparisons are made in step 54, the flow proceeds to step 56. At step 56, survey groups having quality criteria greater than the current group are stored with the corresponding quality criteria. Thus, in this example, the survey group (A, C) is stored with a 9 dB quality criterion and the survey group (B, C) is stored with an 11 dB quality criterion. By performing this storage step, as will be explained in more detail below, it is possible to take into account the possibility of assigning the stored groups to demodulation elements because of the relatively large quality criterion. If survey group (A, C) is first considered for reassignment, its quality criteria is stored first and method 32 proceeds to step 58, described below. After execution of step 58, the survey group (B,
C) is also examined and, since it is greater than the quality criterion of the current group, that quality criterion is also stored in step 56. Further, if it is determined in step 54 that the quality standard of the current group is higher than the quality standard of the survey group investigated in step 53, the flow directly proceeds to step 58,
It does not store the group and its quality criteria in step 56.

Before proceeding with the description, step 5
Note that the processing performed in the description of 4 and 56 is preparation processing for changing demodulation element assignment when the quality standard of the survey group is larger than the current group quality standard. However, in an alternative embodiment, the demodulation element reassignment performed in steps 54 and 56 will not perform the reassignment without a clear quality criterion difference. In this technique, this is called hysteresis and is intended to avoid extreme reallocation. These extreme reassignments are reassignments made due to differences in quality criteria that would be meaningless to do with reassignments, or reassignments caused by frequent changes in group quality criteria. Therefore, the comparison process of step 54 is extended to provide that if the quality criterion of the survey group is clearly larger than the quality criterion of the current group (for example, 3 dB) and if the value of this value can be selected by those skilled in the art, The flow is passed to the reassignment step. In this way, step 5
Hysteresis is effectively applied at 4 and 56. That is, reallocation is performed only in step 54 when the quality criterion of the survey group in question is higher than the quality criterion of the current group by a certain quality criterion value. Hysteresis can be used because each time a reallocation is performed, the corresponding demodulation element is not involved in the communication process (the communication processing time is not zero). The quality criterion threshold for the reassignment is chosen to optimize the trade-off between the idle time of the demodulation element and the larger quality criterion provided by the new path. Further, multiple demodulation elements can be used for reallocation. In this case, the real quality reference threshold for the reallocation may be different for each reallocation (eg, the quality reference threshold for the second reallocation is the quality reference threshold for the first reallocation). May be larger).

In step 58, the demodulation element allocation block 27 determines whether there is a survey group that is not considered. Since the group (B, C) remains even after checking the group (A, C), in such a case, the flow proceeds to step 60, and the flow proceeds to the flow considering the next survey group. Thereafter, the flow returns to step 53. As a result, when control is passed back to step 53, the next survey group is considered according to the steps described above. By repeating the above flow, all survey groups will eventually be considered. This state is detected in step 58, and the flow is passed to step 62. In this example, this condition occurs after both groups (A, C) and (B, C) have been examined.

If a quality criterion exceeding the threshold is detected in step 54 and one or more survey groups are stored in step 56, then in step 62 the group of the highest quality criterion among these survey groups Is assigned to demodulation instead of the current group. For example, when the control passes to step 62, both the survey group (A, C) with the quality standard of 9 dB and the survey group (B, C) with the quality standard of 11 dB are stored, and the current group is ( A, B). As a result, in step 62, the current group (A, B) is replaced by the group (B, C) having the highest quality criterion among the stored survey groups. Thus, in practice, path A is deleted and path C is added instead. In addition, the replaced path becomes a new survey group and joins all other unassigned survey groups. Thereafter, method 32 moves to step 64. Step 64 only indicates that method 32 has been completed. Thus, one of ordinary skill in the art would understand at this completion that all survey groups were considered. It can also be seen that during this process one or more groups are stored for future reassignment, and the assignment of the group with the highest quality criteria among the groups assigned to the elements of the demodulator 28 is performed. Should be. In addition, if the survey group was not stored in step 56 (ie, the current group had better quality criteria than all the survey groups considered), step 62
Is not performed, the demodulation of the current group by the demodulator 28 is continued. Finally, when method 32 is completed, the method is started again when receiver 20 receives a new diversity path.

Having described method 32 in detail, to further describe the operation of the preferred embodiment, step 5
Another example of the operations of 2 and 54 is shown below. For this purpose, the example survey group used above is used again. Here, the current group is composed of (A, B), and the two survey groups are composed of either (A, C) or (B, C). However, the SNR values and the diversity values have been changed to illustrate another aspect of the preferred embodiment. In this example, it is assumed that the same diversity, that is, path A and path B are sent from the same antenna AT1B1 of base station BST1, and path C is sent from antenna AT1B2 of base station BST2.
However, assuming different values, it is assumed that the SNR of path A is 8 dB and the SNR of path B is 10 dB. Therefore, the quality standard of the current group is 18 dB
(Ie, 0 + 8 + 10 = 18 dB).
Further, it is assumed that the SNR of the path C is 2 dB, and the diversity value of 3 dB is given to the base station diversity. In response to these assumptions, by performing step 53 twice, the first survey group (ie,
A, C) with a quality standard of 13 dB (ie, 8 + 2 +
3 = 13 dB), the second survey group (ie,
B, C) is 15 dB (ie, 10 + 2 +
3 = 15 dB). Further, the result of the inquiry processing performed subsequently in step 54 is negative. In other words, none of the survey group's quality standards exceed the current group's quality standards. In response,
In either case, the flow does not go to step 56 and no survey group is stored. The flow is step 58
Is passed to step 62, but since the survey group is not stored, the reallocation process is not performed. Thus, this example shows that while base station diversity is a factor in considering reassignment, it is only one factor affecting this reassignment and takes precedence over all other considerations. It is not.
In particular, in this example, the current group composed of (A, B) is composed only of different paths as a multipath. That is, they all have the same identification parameters (eg, base station BST1, antenna AT1B1). However, both survey groups have base station diversity. Nevertheless, every time step 53 is executed, in subsequent step 54, it is determined that the storage processing of the survey group is not requested even if this base station diversity occurs. Thus, in a subsequent step 62, it is determined that it is not required to reassign the base station diversity group to the demodulation elements. This is because this reassignment does not improve the overall quality standards.

The above description describes the diversity aspect of the preferred embodiment. The above description states that this value represents a score for a change to be made when replacing one or more current paths with one or more new paths. Having considered these aspects, and having described above aspects of the preferred embodiment of the diversity values used in the quality criterion evaluation, some additional details are described below.

As a first additional feature of method 32, in the preferred embodiment, the actual S assigned to each diversity value
The NR gain number may be determined using various techniques. For example, by means of simulation or by actual measurement of the target application (environment, speed, etc.), the improvement of the communication quality provided by each diversity type (for example, reduction of the frame error rate) can be determined in advance, and An SNR value can be assigned. For example, consider the case where paths from different receiver antennas (and / or base stations, etc.) are assigned to demodulation elements instead of another path from the same receiver antenna (and / or base stations, etc.). This assignment is preferred if the SNR of the latter path is, for example, 4 dB or not greater than the SNR of the former. In that case, the diversity value of another receiver antenna is 4
dB, so that the gain of the diversity value is 4
dB. This specific diversity dB value is added to the actual SNR of the path of each group, and the quality standard of the group is determined. Furthermore, if a particular diversity is an undesirable trade-off, the diversity value can be a negative dB value. For example, if the correlation of the paths received by different antennas is not zero, assigning both of these paths will reduce the diversity and will add a negative dB value to the final quality criterion. This negative dB value depends on the degree of correlation and the SNR of the path.
May be dependent on Further, if the multipaths having the same diversity type (other than time diversity) also have a non-zero correlation, it is necessary to add a negative dB value to the combination to reflect the reduced diversity gain. Thus, if the group includes two correlated multipaths, the path criterion may cause the quality criterion to be equal to the sum of the path SNR and a negative dB value. The higher the correlation between the paths, the greater the loss from reduced diversity. Furthermore, this negative dB value may also depend on the degree of correlation and the SNR of the path.

As a second additional aspect of method 32, while the above examples assume only one change in diversity, ie, base station diversity, the preferred embodiment also provides some other diversity. Take into account. Therefore, when considering the change from the assigned path to the new path, it is preferable to also consider the diversity value of another diversity type change. Therefore, if the path is different from the other paths in the group due to different identification parameters, the diversity value of each of these identification parameters is added to the actual SNR of the path in the group, and the quality criterion of the group and I do. Furthermore, the quality reference gain combining various diversity values (eg, receiving antenna and base station diversity) may be different (small or large) from the sum of the diversity values that individually consider each diversity.

As a third additional aspect of method 32, the above example generally describes the case where all M demodulation elements are available for reassignment (ie, K = M).
However, in some cases, K may be smaller than M. In this alternative, the survey group should be determined in step 42 taking into account the fact that few demodulation elements are available. Method 32 performs a different operation in the same manner as described above. In a preferred embodiment,
The only difference is that paths that cannot be reassigned to the combined survey group under consideration cannot be excluded. For example, the demodulator has two demodulation elements,
It is assumed that the current paths are paths A and B. It is further assumed that only one of the two demodulation elements can be reassigned at a time, and paths C and D can also be reassigned. As a result, (A, C), (A, D),
(B, C) and (B, D) only, and (C, D)
Is not included. Thus, the quality criteria of these groups are compared with those of the current group (A, B), and the rest of method 32 performs the operations described above. Further, if path B cannot be reassigned for any reason at a particular point in time, the survey group will determine (A, C) and (A,
D) only.

As a fourth additional aspect of method 32, while the above method improves the assignment of paths to demodulation elements, an alternative embodiment further improves the method,
The number of discriminations required for quality standards is reduced. Specifically, as described previously, in the case of the MDO survey group, the group differs only in the multipath diversity. If so, an alternative embodiment can be constructed by modifying step 53 accordingly. Specifically, for the MDO survey group, step 53 is modified so that the quality criterion is performed only for the survey group that includes the multipath with the highest SNR. Next, the flow proceeds to step 54. With this modification, the remaining MDO survey groups need not be considered for assignment. This is because these survey groups do not have a higher quality criterion than the MDO survey group that contains the strongest multipath.

The idea of MDO survey groups can also be used in step 53 to reduce the number of survey groups of interest. This is when the current group assigned to the demodulation element is an MDO survey group, ie when all current paths are multipath with each other. In this case, step 53 is modified so that the strongest M
Ensure that quality criteria are only performed for the current group and survey group using the DO path combination. If reassignment is not possible for that survey group, there is no need to look at the remaining MDO survey groups that are considering replacing the current group. In general, when a plurality of demodulation element reassignments are considered, the above applies to a combination of weak MDO paths and a combination of strong MDO paths (when considered in terms of total real SNR).

Given the fifth additional aspect of method 32, and considering that the quality criterion of the current group is determined in step 52, also discussed above, method 32 is a method in which one or more demodulation elements are currently assigned. Naturally, the case where it is not included is also included. For example, suppose that at any point in time, there is one unassigned element in a two element demodulator, and the other element (ie, the assigned element) is demodulating path T. Next, it is assumed that the two paths U and V are also targets of allocation. Given such conditions, step 52 determines the quality criterion of the current group consisting only of T. Since T has no diversity (i.e., no other paths in the current group), its quality criterion is only equal to its SNR. However, if two demodulation element reallocations are allowed, the survey groups will be (T, U), (T, V), and (U, V). Therefore, for each of these survey groups, some diversity type occurs because each group has multiple paths. Therefore, it is almost certain that the quality standards of each new group will exceed the quality standards of the current group.
The reason is that each new group has two paths instead of one (hence two SNRs).
Value), and because the new group has more paths, if that diversity value is given, that value will be the cause. As a result, in step 56, a group having a large quality criterion is stored. Thereafter, if there is no group to be investigated and there is no group with a large quality standard, a new group assignment is performed. In the new group, all demodulation elements are used without leaving one or more unused demodulation elements as if the current group (of path T) were analyzed first.

From the above description, it can be seen that the above embodiments provide an improved method and apparatus for assigning paths to demodulation elements in a spread spectrum receiver. further,
Although embodiments of the present invention have been described in detail, various substitutions, modifications, or changes may be made to the above description of various examples without departing from the scope of the present invention.
Indeed, as another example, the preferred embodiment has been described in a CDMA environment, but the invention is applicable to other spread spectrum communication systems. As another example, receiver 20 is shown to include a number of blocks to perform well-known functions, but other corresponding blocks and function types may be used in place of these blocks. it can. As yet another example, the preferred embodiment can be implemented with a user receiver or a base station receiver. Still other examples can be ascertained by those skilled in the art. Therefore, for these reasons, the above examples have been used for purposes of illustrating the preferred embodiments, and are not intended to limit the scope of the invention as defined in the following claims.

With respect to the above description, the following items are further disclosed. (1) A method for operating a spread spectrum communication receiver, wherein a current path group is demodulated by a demodulator, wherein the current path group includes one or more current paths, and the demodulation step includes one or more current paths. Demodulating the current path with a corresponding one or more demodulation elements;
Determining at the receiver one or more survey groups, each survey group including a unique combination of one or more new paths and zero or more current paths; Determining a quality metric of one or more survey groups; and responsive to comparing a quality metric of a group selected from the survey group with a quality metric of a current path group. Selectively assigning a group selected from the group to a corresponding demodulator element instead of the current path group, wherein the quality criterion comprises the power of each path in the group and the plurality of diversity types in the group. A method characterized by being determined by:

(2) The method according to item 1, wherein the power includes a signal-to-noise ratio. (3) The method according to any one of the above items, wherein the plurality of diversity types include base station diversity. (4) The method according to item 3, wherein the plurality of diversity types further include a diversity selected from a group consisting of a transmitter antenna diversity, a receiver antenna diversity, an angle diversity, a code diversity, and a frequency diversity. A method comprising: (5) The method according to any of the above items, wherein the comparing determines whether a quality standard of a group selected from one or more survey groups exceeds a quality standard of a current path group. And how. (6) The method according to any of paragraphs 1 to 4, wherein the quality criterion of the group selected from the one or more survey groups is the quality criterion of the current path group by a hysteresis threshold. A method characterized by determining whether it has exceeded. (7) The method according to any one of the above items, wherein the quality criterion is determined by a sum of a power of each path in the group and a value given to one or more of a plurality of diversity types in the group. A method characterized by the following. (8) The method according to (7), wherein the first pass is the first pass.
And has a first power and a second path is received by the receiver at a second receiver antenna forming receiver antenna diversity, and the first path and the second path The diversity value of the group having a non-zero correlation with respect to the power of 2 and including the first path and the second path has a negative value in response to the non-zero correlation, the first power, and the second power. A method characterized by becoming a value. (9) The method according to (7), wherein the first pass is the second pass.
Has a multipath diversity for the first path, has a non-zero correlation for the first path, the first path has the first power, the second path has the second power, and the first path has The diversity value of the group including the second pass is
A method characterized by becoming negative in response to a non-zero correlation, a first power, and a second power.

(10) The method according to any one of the above items, wherein the one or more survey groups include a plurality of multipath diversity-only groups having paths that differ from each other only with respect to multidiversity.
Determining a quality criterion of one or more survey groups includes determining a quality criterion of only a multipath diversity only group having a maximum power value in the plurality of multipath diversity only survey groups. how to. (11) The method according to any one of the above items, wherein a path in a group selected from one or more survey groups is demodulated by a corresponding element of a demodulator to form estimation information data. Decoding the decoded information data. (12) The method according to any of the above items, wherein the current path group and the one or more survey groups are CDs.
A method comprising including a MA pass. (13) The method according to any of the preceding clauses, wherein before performing the step of determining a quality criterion of one or more survey groups for each of the one or more new paths, an identification parameter of the new path. Further comprising the step of identifying the path parameters, wherein the identification parameters relate to diversity of the path relative to other paths. (14) The method according to any of the above items, wherein before performing the step of determining a quality criterion of one or more survey groups, each path of the current group and the one or more survey groups is despread. The method further comprising the step of: (15) The method according to any one of the above items, wherein the receiver includes a cellular communication receiver.

(16) The method according to any of the preceding clauses, wherein for each path in the current path group and the one or more survey groups, one or more new paths are despread. Identifying the identification parameters of the new path, wherein the identification parameters further comprise the step of diversity of the path with respect to other paths. (17) In the method according to any one of the above items, the plurality of diversity types are a group including a base station diversity, a transmitter antenna diversity, a receiver diversity antenna, an angle diversity, a code diversity, and a frequency diversity. And comparing the quality criterion of the group selected from the survey group to the quality criterion of the current path group, wherein the quality criterion is power and the diversity within the group. Responsive to the sum of the values given to one or more of the formats. (18) The method according to any one of the above items, wherein the step of determining one or more survey groups in the receiver includes the step of determining all paths in the current path group except one path in the current path group. Determining a survey group that effectively reassigns only one element of the demodulator by determining a survey group that includes the method. (19) The method according to any of the above items, wherein each step of determining the quality criterion is responsive to one or more identification parameters corresponding to one or more paths in the group for determining the quality criterion. Determining a quality criterion, wherein each of the one or more identification parameters has a predetermined individual diversity value. (20) The method according to Item 21, wherein for a group having a plurality of paths whose quality criteria are determined and identification parameters are different, a combination of a plurality of identification parameters is a sum of individual diversity values of each identification parameter of the combination. A predetermined combination diversity value different from the above. (21) The method according to any one of the above items, wherein the step of selectively assigning a group selected from one or more survey groups to each element of the demodulator instead of the current path group is performed. A method comprising selecting one survey group from one or more survey groups having a quality criterion greater than a quality criterion of each of one or more survey groups and greater than a quality criterion of a current path group.

(22) A communication receiver, which is a circuit for demodulating a current path group, wherein the current path group is 1
The demodulation step includes one or more current paths, and the corresponding one
A circuit including a step of demodulating one or more current paths with one or more demodulation elements, and a circuit for receiving one or more survey groups at a receiver, wherein each survey group comprises one or more.
A circuit including a unique combination of one or more new paths and zero or more current paths; a circuit for determining quality criteria for the current path group; a circuit for determining quality criteria for one or more survey groups; A circuit for selectively assigning a group selected from the survey group to a corresponding element of the demodulator instead of the current path group based on a comparison between the quality criteria of the selected group and the quality criteria of the current path group. Is a communication receiver determined by the power of each path in the group and a plurality of diversity types in the group. (23) The receiver according to paragraph 22, wherein the power includes a signal-to-noise ratio. (24) The receiver according to paragraph 22 or 23,
The receiver wherein the plurality of diversity formats include base station diversity. (25) The receiver according to item 24, wherein the plurality of diversity formats include a diversity selected from a group consisting of a transmitter antenna diversity, a receiver antenna diversity, an angle diversity, a code diversity, and a frequency diversity. A receiver further comprising:

(26) Spread spectrum communication receiver (2
Method (32) for operating 0). This method uses a demodulator (2
8) The method for demodulating a current path group in 8), wherein the current path group includes one or more current paths, and the demodulating step demodulates one or more current paths with a corresponding one or more demodulation elements. including. The method also includes identifying (42) one or more survey groups at the receiver, each survey group including one or more new paths and zero or more unique combinations of current paths. I have. In addition, the method includes the quality criteria of the current path group (52) and the quality criteria of one or more survey groups (5).
3) is determined. Further, the method assigns the selected group from the survey group to the corresponding element of the demodulator instead of the current path group based on a comparison of the quality criteria of the group selected from the survey group with the quality criteria of the current path group ( 62). The quality criterion is determined by the power of each path in the group and a plurality of diversity types in the group.

[Brief description of the drawings]

FIG. 1 illustrates an example of cellular communication with two dual antenna base stations and one single antenna mobile user station.

FIG. 2 is a functional block diagram of a receiver according to a preferred embodiment;

FIG. 3a shows a preferred method of operating the receiver of FIG. 2 for assigning a path to the demodulation elements of the receiver.

FIG. 3b shows a preferred method of operation of the receiver of FIG. 2 for assigning paths to demodulation elements of the receiver.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Cellular communication system 20 Receiver 22 Input 24 Despreading block 26 SNR measurement block 27 Demodulation element allocation block 28 Demodulator 29 Path diversity discrimination block 30 Decoder

Claims (2)

[Claims] 1. A method of operating a spread spectrum communication receiver, comprising: demodulating a current path group with a demodulator, wherein the current path group includes one or more current paths; Demodulating the current path with one or more corresponding demodulation elements; and determining at least one survey group at the receiver, wherein each survey group includes one or more new paths. Determining a quality criterion of the current path group; determining a quality criterion of one or more survey groups; and determining a quality criterion of one or more survey groups. In response to comparing the quality criteria with the quality criteria of the current path group, select a group from one or more survey groups. Selectively assigning to a corresponding demodulator element instead of the current path group, wherein the quality criterion is determined by the power of each path in the group and the plurality of diversity types in the group. how to. 2. A communication receiver, comprising: a circuit for demodulating a current path group, wherein the current path group includes one or more current paths; A circuit including a step of demodulating one or more current paths, and a circuit receiving one or more survey groups at a receiver, each survey group comprising one or more new paths and zero or more current paths. Circuit that determines the quality criteria of the current path group; circuit that determines the quality criteria of one or more survey groups; quality criteria of the group selected from the survey groups and quality criteria of the current path group And selectively assigning a group selected from the survey group to the corresponding element of the demodulator instead of the current path group based on the comparison with For example, quality standards, communication receiver, characterized in that determined by a plurality of diversity formats in power and groups of each path in the group.